Effect of fertilizer strategies on the grey water footprint in rain-fed and irrigated agriculture

Transcription

1 Effect of fertilizer strategies on the grey water footprint in rain-fed and irrigated agriculture SWAT 2015 PULA/SARDINIA/ITALY Researcher: A.D. Chukalla, PhD candidate Supervisor: Dr. M. S. Krol, Associate Professor Promoter: Prof. Dr. Ir. A.Y. Hoekstra, Professor 25/06/ June,

2 Content Introduction Objective Data Methods Results Conclusions Footer text: to modify choose 'View' (Office 2003 or earlier) or 'Insert' (Office 2007 or later) then 'Header & Footer' 2

3 Introduction The water footprint is a comprehensive indicator of freshwater resources appropriation, showing water consumption volumes by source and polluted volumes by type of pollution. It composes the green, blue and grey components. (Hoekstra, 2011). Water footprint(wf) reduction is increasingly required in the face of increasing water scarcity and in the move to close supply-demand gap for fresh water. Footer text: to modify choose 'View' (Office 2003 or earlier) or 'Insert' (Office 2007 or later) then 'Header & Footer'

4 Introduction Understanding water resources use by source (rainwater, irrigation water from surface and groundwater, water from capillary rise) is vital for water resources management. Falkenmark and Rockström (2006) and Hoekstra et al. (2011). Green/Blue WF Grey WF for nonpoint source Footer text: to modify choose 'View' (Office 2003 or earlier) or 'Insert' (Office 2007 or later) then 'Header & Footer' 4

5 Introduction Agriculture contributes, 92% of the global fresh water footprint (Mekonnen, M.M. and Hoekstra, A.Y. (2011)) Irrigation withdraws 70% of fresh water resources (Fischer et al., 2007). (AQUASTAT FAO) Plants use only 10 to 30% of the fresh water supply for biomass formation(howell et al., 2001; Wallace, 2000). Footer text: to modify choose 'View' (Office 2003 or earlier) or 'Insert' (Office 2007 or later) then 'Header & Footer' 5

6 Introduction Water footprint of irrigated crop production can be reduced by (1) increasing yield, and (2) minimizing losses (Hoekstra, 2013). Scale: Basin, Farm, Field WF =f(managements) Footer text: to modify choose 25/06/2015 'View' (Office or earlier) or 'Insert' (Office 2007 or later) then 'Header & Footer'

7 Objective to explore the scope for reducing the water footprints of growing crops by a systematic model based assessment of management practises at field and basin scale. (1) to explored the potential for reducing the greenblue water footprints of growing crops (p1). (2) to explore the effect of fertilizer strategies on the grey water footprint of growing crops (p2). 7

8 Data Climate Humid Crop parameters (Potato, tomato and maize FAO database and local conditions Arid Soil and field data measurement Groundwater

9 Method (p1) Management options 1. Four irrigation techniques: Furrow, Sprinkler, Drip and Subsurface drip (SSD); 2. Three irrigation strategies: full irrigation, deficit irrigation & supplementary irrigation; + rain-fed; 3. Three mulching practices: no mulching, organic & synthetic mulching. Modelling AquaCrop & WF accounting Effects Green and Blue WF of growing crops Cases: Four environments, three types of years, three soils and three crops Footer text: to modify choose 'View' (Office 2003 or earlier) or 'Insert' (Office 2007 or later) then 'Header & Footer'

10 Cases: Four environments, three types of years, three soils and three crops Environment (Location) Arid (Eilat, Israel) Semi-arid (Badajoz, Spain) Sub-humid (Bologna, Italy) Humid (Eden, United Kingdom) Soil Loam Sandy loam Silty-clay-loam Loam Sandy loam Silty-clay-loam Loam Sandy loam Silty-clay-loam Loam Sandy loam Silty-clay-loam Type of years Dry Normal Wet Dry Normal Wet Dry Normal Wet Dry Normal Wet Crops Maize, potato and tomato Maize, potato and tomato Maize, potato and tomato Maize, potato and tomato Groundwat er Deep Deep average 1.5 m Deep

11 Method Green and blue soil water separation dsg Sg R R (Dr ET) RO dt S I R dsb-cr Sb-CR CR (Dr ET) dt S ds dt b-i Sb- I (Dr ET) S I RO I I R WF n (ET b I ) i WF b I i 1 Y n (ET b CR ) i WF b CR i 1 Y g n ( ET i 1 Y g ) i Footer text: to modify choose 'View' (Office 2003 or earlier) or 'Insert' (Office 2007 or later) then 'Header & Footer'

12 Rain, Capillary rise(cr), Irrigation(Irr) (mm) Water content in the maximum effective root zone (mm) (Results (p1): green blue soil water separation Date, Crop growing period 22-Mar 21-Apr 21-May 20-Jun 20-Jul FC (mm) PWP (mm) Mar 21-Apr 21-May 20-Jun 20-Jul Crop growing period CR mm S total Irri mm Rain mm Sg Sb Figure : The green (Sg) and the blue (Sb) soil water stocks/storages at Bologna, Semi-humid environment, for average year/2001/

13 WF (m 3 /t) (Results (p1): Effect of the management options on ET, Y and WF Maize Potato Tomato Evapotranspiration (mm) Figure: Effects on WF from the whole experiment

14 Yield (ton/ha) Yield (ton/ha) Results (p1): Effect of the management options on ET, Y and WF Sprinkler Furrow Drip SubsurfaceDrip Supplementary Deficit Evapotranspiration (mm) Full Figure: ET-Y relationship for irrigation techniques with no mulching practice Rain-fed Without mulching Organic Synthetic supplementary ET = saving Y =f(t )=yield increase Full deficit Evapotranspiration (mm) Figure: ET-Y plot for mulching practices at rain-fed and drip irrigated field. Case: potato, loam soil, normal year, Semi-arid environment (Badajoz Spain). 14

15 Results (p1) Effect of the management options on ET, Y and WF 150 Green WF (m 3 /t) Blue WF (m 3 /t) Yield (ton/ha) 26 ton/ha 27 ton/ha Rain-fed Supplementary irrigation Deficit irrigation Full irrigation 11 ton /ha Rainfed 18 ton/ha Supplementary irrigation Deficit irrigation Full irrigation Rainfed ET-green (mm) Blue water added 215m 3 /ha Yield increase 7ton/ha Supplementary irrigation ET-blue (mm) Blue Water saving 144m 3 /ha Yield reduction 1ton/ha Deficit irrigation Full irrigation Figure: Effects of the irrigation strategies with drip on Yield, green and blue WF. Case: potato, loam soil, normal year, Semi-arid environment i.e. Badajoz Spain.

16 Results (p1): Reduction in the total WF Reference (furrow irrigation with full irrigation and without mulching practice) The box and whisker plot shows the WFreduction values for the whole cases: (a) whole management practices; (b) four irrigation techniques, with FI and NoML; and a (a) four irrigation techniques, with DI and NoML. b c 16

17 Furrow Sprinkler Drip SubSDrip Furrow Sprinkler Drip SubSDrip Furrow Sprinkler Drip SubSDrip Furrow Sprinkler Drip SubSDrip Drip & SubSDrip Drip & SubSDrip Total WF reduction (%) Results (p1): Reduction in the total WF Full Irrigation No mulching Arid Semi arid Subhumid Humid Avg of all cases Deficit Irrigation No mulching Full Irrigation Organic mulching Deficit Irrigation Organic mulching FI DI Synthetic mulching Figure: The mean total WF reduction categorized by the environments for the whole cases 17

18 Furrow Sprinkler Drip SubSDrip Furrow Sprinkler Drip SubSDrip Furrow Sprinkler Drip SubSDrip Furrow Sprinkler Drip SubSDrip Drip & SubSDrip Drip & SubSDrip Total WF reduction (%) Results (p1): Reduction in the green-blue WF Green WF reduction Blue WF reduction Total WF reduction Full Irrigation No mulching Deficit Irrigation No mulching Full Irrigation Organic mulching Deficit Irrigation Organic mulching FI DI Synthetic mulching Figure: The mean green, blue and total WF reduction; for the whole cases 18

19 Conclusions The average reduction in the consumptive WF is: 8-10% if we change from the reference to drip or SSD; 13% when changing to OML; 17-18% when moving to drip or SSD in combination with OML; and 28% for drip or SSD in combination with SML. Reduction in overall consumptive WF always goes together with an increasing ratio of green to blue WF. The WF of growing a crop for a particular environment is smallest under DI, followed by FI, SI and rain-fed.

20 Conclusions Growing crops with sprinkler irrigation has the largest consumptive WF, followed by furrow, drip and SSD. Furrow irrigation has a smaller consumptive WF compared with sprinkler, even though the classical measure of irrigation efficiency for furrow is lower.

21 Grey water footprint component Simulating the effect of fertilizer strategies on the grey water footprint of growing crops (p2).

22 Method (p2) Management practices Modelling Effects 1. Moisture supply strategies: irrigated (full irrigation) and rain-fed; 2. Fertilizer strategies: types: mineral and organic fertilizer Quantity: without, existing, Apex & Global WF accounting standard Grey WF of growing crops Cases: Semi-arid environment, three types of years, three soils and potato crop Footer text: to modify choose 'View' (Office 2003 or earlier) or 'Insert' (Office 2007 or later) then 'Header & Footer'

23 Method (p2) Uptake by crop Green and blue water supply Figure: soil water nutrient balance

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25 Thank You